Effective Irrigation Practices for Optimal Kiwi Plant Growth

Kiwi plants (Actinidia deliciosa) are native to regions with ample rainfall and high humidity. It is considered a crop with high water needs, requiring a consistent water supply to thrive, particularly during dry periods. Kiwi plants need well-drained soil with good water retention to maintain moisture without becoming waterlogged. To accomplish that, farmers can take measures to improve soil health (improve water holding capacity) and adjust the irrigation schedule according to the plant's needs, depending on the age, developmental stage, environment, and soil type, to maximize production efficiently. Generally, kiwi plants require about 800-1200 mm of water annually to ensure healthy growth and fruit production. Young plants require less water than mature vines, but consistent moisture is still crucial for establishing strong roots. Let us see when and how this amount should be supplied to the kiwi plants throughout the season.

Water Requirements of Kiwi - Developmental Stage

Dormancy (Winter): Minimal water is needed by the kiwi plants during this period. The grower should ensure the soil remains moist to prevent root desiccation.
Bud Break and Flowering (Spring): Sufficient water is crucial to support bud development and flowering. Water stress during this stage can lead to poor fruit set and reduced yields. If the rainfall during that period is not sufficient to cover the plants' water needs, farmers are advised to start irrigating to support new growth and flowering. Kiwi growers can irrigate every 10-12 days, providing about 25-30 mm of water per session. This should be adjusted depending on the rainfall.
Fruit Development (Early Summer): During this stage, the fruit forms and the enlargement starts. Kiwifruit growers should maintain consistent soil moisture and irrigate deeply and regularly to ensure proper fruit size and quality.
Fruit Ripening (Late Summer to Early Fall): You can continue regular irrigation to ensure fruits develop fully and reach the maximum sweetness levels (depending on the variety). Experienced kiwifruit growers and agronomists say that during July and August (North hemisphere), they apply 800-1000 L of water in 2 doses in 3-4 day intervals within a week.
Post-Harvest (Fall): You can gradually reduce irrigation as the plants prepare for dormancy, but it is better not to allow the soil to dry out completely. Some extra irrigation might be needed in the warmest regions with sandy soils.

Avoid Common Irrigation Mistakes in a Kiwi Field

Supplying the kiwi plants with the amount of water they need per developmental stage is key to a high yield and a vigorous crop. Water stress or excessive water supply can cause significant problems. Specifically, kiwi are sensitive to excessive water and waterlogged soils, which can lead to root rot and other diseases. As a result, ensuring proper drainage to prevent standing water in the kiwi field is essential. On the other hand, inconsistent or insufficient watering can stress the plants, reducing fruit size and quality.

Growers should monitor soil moisture levels regularly and adjust irrigation accordingly. Sensors or manual methods can be used to check soil moisture levels.

Tips:

In sandy soils, increase the irrigation frequency but reduce the amount of water per session to prevent leaching.
You can water early in the morning to minimize evaporation and ensure plants have enough moisture throughout the day.
You can avoid watering in the late afternoon or evening to reduce the risk of fungal diseases.

To protect and maintain soil moisture, some kiwifruit farmers apply mulch around the base of the plants and cover crops between plant rows to improve soil health and reduce weed growth and soil erosion.

Effective Irrigation Practices for Optimal Kiwi Plant Growth

Types of Irrigation Systems for Kiwi Plants

According to the University of California, approximate safe levels for irrigation water are:

Chloride less than 70 ppm.
Bicarbonate less than 200 ppm.
Boron less than 0.25 ppm.
Sodium less than 50 ppm.
Electrical conductivity EC x 103 less than 0.75.

Farmers should regularly test water sources to ensure they meet quality standards. Keep in mind that the water needs of Kiwi plants are maximized during warm months (summer), which coincides with fruit development and enlargement. During that period, irrigation is essential. However, in many kiwi production regions, there is significant competition for the available water that is supplied to the farmers at specific times. The farmer should take measures to make the best use of the available water and protect the soil moisture. Many kiwi growers prefer irrigation systems with higher precision to maximize water use efficiency.

Drip Irrigation:

It delivers water directly to the root zone, minimizing water loss due to evaporation and runoff. It is highly efficient, promotes deep root growth, and is considered the most efficient and effective system for kiwi plants. Kiwi growers also prefer using this system because it reduces weed growth by limiting water distribution to the immediate root zone (making weed management easier), but it can also be used for fertigation. While the initial setup costs might be higher than the other systems, its benefits and the high value of the kiwifruit are sufficient to convince farmers.

Micro-sprinklers:

It is another relatively popular choice in regions with dry climates. Micro sprinklers provide broader coverage and can help increase humidity around the plants, which is beneficial in dry climates. They are less efficient than drip systems but still conserve water compared to traditional methods.

Sprinklers can be used in kiwi fields but are usually not preferred. They might be useful in colder regions with higher frost risk during spring for frost protection during critical growth stages.

Furrow Irrigation:

Furrow irrigation involves creating furrows or channels along the field where water flows by gravity to irrigate the kiwi plants. It can be used in large-scale operations, especially where water is plentiful and labor costs are low. It is less efficient than drip or micro-sprinklers but can be effective with proper management. Flood irrigation is generally not recommended for kiwifruit due to its inefficiency and the potential for waterlogging, which can harm the roots of kiwifruit plants.

Proper irrigation is crucial for the successful cultivation of kiwi plants. Understanding the water needs at different growth stages and choosing the right irrigation system can significantly enhance yield and fruit quality. Drip irrigation is the preferred method for its efficiency and effectiveness, but micro-sprinklers and furrow irrigation can also be suitable depending on specific conditions and resources.